Backpack



FIG. 1 is a front, left perspective view of a backpack showing my new design;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a right side view thereof;

FIG. 5 is a left side view thereof;

FIG. 6 is a top view thereof;

FIG. 7 is a bottom view thereof; and,

FIG. 8 is an enlarged view of FIG. 2 with unclaimed subject matter omitted.

The uneven length broken lines immediately adjacent to the shaded area represent the boundaries of the claim and form no part of the claimed design. The unevenly spaced broken lines within the shaded area and the evenly spaced broken lines showing stitching and other parts of the backpack are for the purposes of illustrating environment and form no part of the claimed design. 

CLAIM The ornamental design for a backpack, as shown and described. 